My 2004 Grand Cherokee has started to whine. From very low speeds all the way up to high speeds. It is dependent on wheel speed, not engine speed. It sounds like it is coming from the front of the vehicle.
Any suggestions on what to check for?

i have the same prob with my 2000 zj quadradrive, i've been driving it for a month like this now and it hasn't got any worse. will it get worse??

i took it to a few mechanics they said its the diff. one told me he wants to replace the whole thing, is that a good idea? i'd rather keep it as original as i can as i don't trust a rebuilt diff, cuz it mite happen again soon...

the noise mine makes starts as 30 km/hr like yours and it whines and as i get up to about 60 km/hr, the whining sorta rattles, and as i let go of the gas and decrease in speed, the whining sounds like its winding down as opposed to how its winding up as i go past 30...maybe someone can diagnose from that if my case is cracked or its just something inside the case?